1. Field of the Invention.
The present invention relates to a device to deliver or administer medication to a patient, and more particularly, concerns a syringe pump intended for the delivery or administration of such medications.
2. Background Description
Hospitals typically use intravenous (I.V.) administration sets to deliver liquid medication to patients. When the patient needs medication, such as an antibiotic, standard practice until recently has been to deliver such a drug by a "piggy-back" drip into the primary infusion line. Recently, however, the procedure for delivering antibiotics and other drugs to patients on I.V. therapy has been changing Mechanically driven syringes, oftentimes called or referred to as syringe pumps, are available to hospitals and other users for the administration of drugs and other liquid medications which the patient may require.
Indeed, a wide variety of syringe pumps and other liquid medication delivery devices are becoming available. With particular reference to a syringe pump, as that term is used herein, such pump employs a conventional or modified syringe which holds the liquid medication, the plunger of which is typically driven or pushed by a mechanized element for the automatic delivery of the liquid contents within the syringe. These syringe pumps are now available in battery-powered form, include microprocessor technology for programming rates or times of medication delivery, have digital displays for ease of viewing by the user or the patient, include alarm circuits in the event of duty cycle completion, failure, or line occlusion, and other features to facilitate the operation or performance of the syringe pump. As these syringe pumps become more sophisticated, the technological advances oftentimes have a tendency to increase the expense of making and using the device, increase the complexity of use, and increase the opportunities for breakdown and repair if one or more of the operational elements break down.
For example, many existing syringe pumps include an occlusion circuit for producing an alarm (visual and/or audible) when the syringe cycle has been completed, if the I.V. line or syringe is occluded or if there is a system failure. One common mechanism for activating the occlusion circuit has been the use of one or more switches which are tripped after the syringe plunger passes a certain point during its travel into the syringe barrel. In other instances, the syringe is mounted on a spring-loaded platform which is subject to a small linear movement after a certain force level has been reached. Thus, if the plunger being pushed into the syringe barrel either reaches the bottom of the syringe or cannot expel the liquid contents due to an occlusion in the line, the force against the plunger causes the entire spring-mounted syringe to move in linear fashion This movement, in turn, either trips a switch or may be sensed by position-sensitive sensors to send a signal to the occlusion circuit so that the automatic operation of the syringe pump may be terminated. Improvements in such an occlusion circuit are not only desirable, but are still being sought, in order to reduce the expense of the elements heretofore needed in such an occlusion circuit, as well as to eliminate the need for switches or sensing elements in order to achieve the desired results.
Some syringe pumps accept different size syringes for carrying different kinds or amounts of liquid medication. It is known to have an automatic measurement or sensing of the syringe size positioned in the syringe pump so that control of the rate and time of medication delivery may be automatically determined as a function of the size of the syringe placed in the syringe pump. Improvements in the sensing mechanism for accommodating and measuring different size syringes are desirable to provide a superior product.
Many available syringe pumps employ membrane switches on the front panel which the user depresses with a finger in order to activate a function of the syringe pump. These membrane switches, which include both on and off capabilities, are relatively expensive, and as the number of these switches increases with the sophistication of the functions, further it increases the expense of the entire device. Accordingly, improvements in the panel switches or buttons for access by the user are also desirable, and are being sought.
It is toward such improvements, as mentioned above, as well as other improvements to be pointed out below, that the present invention is directed.